ARM: dts: imx7s: Specify #io-channel-cells in ADC nodes

Specify #io-channel-cells in ADC nodes. Needed to be able to reference
them by phandle.
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7s.dtsi

@@ -670,6 +670,7 @@ adc1: adc@30610000 {
 				interrupts = <GIC_SPI 98 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX7D_ADC_ROOT_CLK>;
 				clock-names = "adc";
+				#io-channel-cells = <1>;
 				status = "disabled";
 			};
 
@@ -679,6 +680,7 @@ adc2: adc@30620000 {
 				interrupts = <GIC_SPI 99 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX7D_ADC_ROOT_CLK>;
 				clock-names = "adc";
+				#io-channel-cells = <1>;
 				status = "disabled";
 			};